In current downhole drilling operations, it is desirable to maintain data communication between the drill tool and a controller device at the surface, so that drilling parameters may be modified in real-time, as the drilling process progresses. This communication is commonly provided through the drill string, typically using electric or fiber-optic cables. Unfortunately, the relative rotation between the drill tool and other portions of the drill string (e.g., a tool string) makes it difficult to maintain a communication channel through the gap formed between the drill tool and the rest of the drill string.
Some attempts at forming a communication channel involve using electrically conductive brushes to make contact between the drill tool and the drill string, but have limited success due to the fast ‘wear and tear’ of the contacts, and the noise in the communication channel. Other attempts to establish a contact-less communication channels encounter the problem of finding adequate light sources and detectors that may work at the highly demanding environmental downhole conditions in the wellbore, such as high pressure, high temperature, and highly absorbing (opaque) materials.
In the figures, elements having the same or similar reference numerals refer to the same or similar function, or step, unless otherwise noted.